OAKLAND — An underground electrical cable failure that sent smoke billowing from a manhole cover Wednesday in downtown Oakland prompted a brief shelter in place as fire crews searched for the source of the problem.

Crews responded about 9:42 a.m. to reports of smok, coming from a manhole in the 200 block of 12th Street in downtown Oakland.

The smoke was apparently caused by an underground 120-volt electrical line failure, PG&E officials said.

Residents and businesses were told to shelter in place when the smoke was first spotted, and at least two nearby traffic signals were affected.

No injuries were reported. Streets in the area were blocked off while crews inspected the cable line.